Production of acetic acid



MW 30, E933 R. MULLER m Ax.. 3,93%92@ PRODUCTION oF ACETIG ACID Filed Nov. l2, 1950 Patented May 30, 1933 UNITED STATES l PATENTy OFFICE RICHARD 0F MANNHEIM, AND ALFRED LBKE A ND HERMANN DIETERICH, or MANNHEIM-WALDHOF, GERMANY, AssIGNons To c. F. BOEHRINGER a soEHNE G. M. B. E., oF MANNHEIM-WALDHOF, GERMANY `Application led November 12, 1930, Serial No. 495,152, and` in Germany November 15, 1929.

Our invention refers to the production of acetic acid, more especially by oxidation of acetaldehyde. It is an object of our invention to provide means whereby a purer product can be obtained in a simpler manner and at less cost than was hitherto possible.

As is well known to those skilled in the art, the oxidation of acetaldehyde to form acetic acid requires the aldehyde to be oxidized substantially quantitatively and the oxidizing agents vto be fully utilized in order that a satisfactory economy of the process be obtained. If the reaction shall be carried through continuously with the aid of oxygen' t or gases containing same, it appears obvious to lead the oxidizing gases 1n countercurrent to the acetaldehyde. It is true that in this manner acetic acid free from acetaldehyde can be obtained, however, the oxygenv which is supplied in excess is not fully utilized and being soiled with gaseous byproducts, which will always form in small quantities, will carry along part of the volatile acetaldehyde which has escaped conversion.

In order to obviate `these drawbacks we introduce the oxidizing agent, such as oxygen or a gas mixture containing same, into a body of acetaldehyde and we then`v lead the freshly formed acetic acid and unconverted acetaldehyde in countercurrent to the oxidizing agent and further take care to maintain contact between lthe vapor of acetaldehyde, which has escaped conversion, and the oxidizing agent, which has not been consumed in the first reaction, until substantially all acet-y aldehyde has been converted into acetic acid by interaction with an oxidizing agent still available. In practicing our invention We prefer using apparatus, such as illustrated diagrammatically in section by way of example in the accompanying drawing.'

Referring to the drawing, 1, l are ,five vessels, each provided with agitating means 2, these vessels being arranged in series and being interconnected by an overflow 5 and by gas pipes 6. These reaction chambers are arranged on different levels, chamber A being the lowermost, chamber E the uppermost. Obviously liquid will thus be able to flow from E through D, C and B to A.

3 is a container filledwith acetaldehyde and 4 is a pipe connecting samewith the top of the middle chamber C.

The acetaldehyde which may be dissolved in asuitable solvent, Ifor instance a chlorinated hydrocarbon, is continuously supplied to the middle chamber C, which may be charged With acetaldehyde or a .solution thereof or with acetic acid and contains a catalyst adapted to causereaction between the reagents. Means (not shown) are provided for heating and for cooling each chamber and vessel'l. Oxygen or some other suitber4 A through pipes 6 and after having passed through the liquid contained in this 'chamberwill pass over into chamber'B, from here into chamber C and so on. In chamber C the acetaldehyde supplied from the container 3 reacts with the oxygen or the like entering the vessel 1 from the chamber B and under the action of the catalyst -is oxidized to form acetic acid. In proportion to'I its formation this acid together with part of y.the acetaldehyde,- which has escaped conver? fsion, runs into the chamber B through the overflow tube 5, which also contains some catalyst, and here meets more concentrated oxygen than was supplied to chamber C. Therefore, in the chamber B thel rest of the acetaldehyde, which was carried away lby the freshly formed acetic acid, is oxidized almost completely. The liquor in chamber B escaping through overflow pipe 5 passes 'over into chamber A, where the last traces of acetaldehyde are oxidized in contact with the fresh oxygen or the like entenig this chamber and pure acetic acid to 'which may be admixed the solvent used in/th'e reaction leaves this chamber through the overiow pipe 5. The

bonic acid, etc., and of the vapor of acetalde- 4 hyde, which has escaped conversion, andl is being carried along by the gases. In chamber able oxidizing agent is supplied to the vcham-Y with the size of the vessels, the quantity of 4 acetaldehyde to be converted per hour etc., but in all cases care must be taken to keep thev acetaldehyde vapor which has escaped` conversion in contact with the oxygen which has not been consumed in the reaction until the acetaldehyde'has been fully oxidized and and oxygen fully consumed On the other hand the liquid acetaldehyde mixed with the freshly formed'acetic acid in the primary reaction chamber is brought in contact with fresh oxygen or the like to such an extent that no unconverted acetaldehyde can escape from the lowermost reaction chamber.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacriiicing the advantages thereof.

1. In the production of acetic acid from acetaldehyde, the continuous process which comprises establishing and maintaining a plurality of reaction zones, connected in series and containing bodies of liquid, passing acetaldehyde into a reaction zone midway of said series, passing an oxidizing gas through lsaid series of reaction zones and through each of said bodies of liquid, under conditions causing substantially complete oxidation of `any acetaldehyde to acetic acid, and passing the liquid reaction products through each of said zones in countercurrent to said flow of oxidizing gas.

2. In the production of acetic acid from acetaldehyde, the continuous process which comprises establishing and maintaining a series `of reaction zones containing bodies of liquid at varying levels, the said bodies of liquid comprising products of the reaction, passing the liquid reaction products downwardly of said series through each of said zones, passing oxidizing gases and gaseous reaction products through'said bodies of liquid upwardly of said series, under conditions causing substantially complete oxidation of acetaldehyde to acetic acid, and introducing acetaldehyde midway ,of said series.

' 3. In the production of acetic acid from acetaldehyde, the continuous process which comprises establishing and maintaining a series of reaction zones containing bodiesl of a liquid comprising products of the reaction and an oxidation catalyst, introducing acetaldehyde' midway of said series, passing an oxidizing gas into and through said bodies of liquid in said series, under conditions causin substantially complete oxidation of acetal ehyde Ito acetic acid, and passing liquid reactlon products through each of said zones in countercurrent to said fiow of oxidizing gas.

4. In the production of acetic acid from acetaldehyde, the continuous process which comprises establishing and maintaining a series of reaction zones containing bodies of a liquid comprising products of the reaction and maintained under agitating Iconditions, introducing acetaldehyde midway of said series, passing liquid reaction products through each of said zones to one end of said series, introducing oxidizing-gases at said end and passing said oxidizing gases, to-

ether with any gaseous reaction products, rom said end .to the opposite end into and through said bodies of liquid and in countercurrent tofsaid flow of liquid reaction products under conditions affording substantially complete oxidation of said acetaldehyde.

5. The process of claim l wherein the acetaldehyde is dissolved in a solvent such as a chlorinated hydrocarbon..

6. In the production of acetic acid from acetaldehyde, the Continuous process which comprises passin an oxidizing gas into and through a body o liquid containingacetaldehyde and products of the reaction, under conditions causing oxidation of acetaldchyde to acetic acid, passing acetaldehyde into said body of liquid, passing the gases exhausted from said liquid, containing unconsumedl oxygen and unconverted acetaldehyde vapors, into and through a series of bodies of liquid containing products 'of the -reaction until substantially all acetaldehyde has been converted into acetic acid and passing products of'reaction in counter current to said gases into said first body of liquid.

7. The process of claim 1 wherein at least one of the said bodies of liquid contains an oxidation catalyst.

In testimony whereof We aiix Vour signatures.

RICHARD MLLER. ALFRED LBKE. HERMANN DIETERICH. 

